Superconducting gap structure of the 115s revisited

Density functional theory calculations of the electronic structure of Ce- and Pu-based heavy fermion superconductors in the so-called 115 family are performed. The gap equation is used to consider which superconducting order parameters are most favorable assuming a pairing interaction that is peaked at (π, π, qz)—the wavevector for the antiferromagnetic ordering found in close proximity. In addition to the commonly accepted dx2?y2 order parameter, there is evidence that an extended s-wave order parameter with nodes is also plausible. We discuss whether these results are consistent with current observations and possible measurements that could help distinguish between these scenarios.     

A mixed-entropic uncertainty relation

We highlight the advantages of using simultaneously the Shannon and Fisher information measures in providing a useful form of the uncertainty relation for the position-momentum case. It does not require any Fourier transformation. The sensitivity is also noteworthy.     

Interaction of glutathione S-transferase with hypericin: A photophysical study

The photophysics of hypericin have been studied in its complex with two different isoforms, A1-1 and P1-1, of the protein glutathione S-transferase (GST). One molecule of hypericin binds to each of the two GST subunits. Comparisons are made with our previous results for the hypericin/human serum albumin complex (Photochem. Photobiol. 1999, 69, 633-645). Hypericin binds with high affinity to the GSTs: 0.65 microM for the A1-1 isoform and 0.51 microM for the P1-1 isoform (Biochemistry 2004, 43, 12761-12769). The photophysics and activity of hypericin are strongly modulated by the binding protein. Intramolecular hydrogen-atom transfer is suppressed in both cases. Most importantly, while there is significant singlet oxygen generation from hypericin bound to GST A1-1, binding to GST P1-1 suppresses singlet oxygen generation to almost negligible levels. The data are rationalized in terms of a simple model in which the hypericin photophysics depends entirely upon the decay of the triplet state by two competing processes, quenching by oxygen to yield singlet oxygen and ionization, the latter of these two are proposed to be modulated by A1-1 and P1-1.     

Superconductivity and topological Fermi surface transitions in electron-doped cuprates near optimal doping

We discuss evolution of the Fermi surface (FS) topology with doping in electron-doped cuprates within the framework of a one-band Hubbard Hamiltonian, where antiferromagnetism and superconductivity are assumed to coexist in a uniform phase. In the lightly doped insulator, the FS consists of electron pockets around the (π,0) points. The first change in the FS topology occurs in the optimally doped region when an additional hole pocket appears at the nodal point. The second change in topology takes place in the overdoped regime (∼18%) where antiferromagnetism disappears and a large (π,π)-centered metallic FS is formed. Evidence for these two topological transitions is found in recent Hall effect and penetration depth experiments on Pr_2-xCe_xCuO_4-δ (PCCO) and with a number of spectroscopic measurements on Nd_2-xCe_xCuO_4-δ (NCCO).     

Molecular alteration in drug susceptibility against subtype B and C-SA HIV-1 proteases: MD study

Structural Chemistry - HIV-1 protease (HIV PR) is one of the most promising targets for anti-HIV drug discovery. Extensive anti-HIV drug discovery research was focused on HIV-1 subtype B protease...     

Design and analysis of a first order time-delayed chaotic system

The present paper reports the design and analysis of a new time-delayed chaotic system and its electronic circuit implementation. The system is described by a first-order nonlinear retarded type delay differential equation with a closed form mathematical function describing the nonlinearity. We carry out stability and bifurcation analysis to show that with the suitable delay and system parameters the system shows sustained oscillation through supercritical Hopf bifurcation. It is shown through numerical simulations that the system depicts bifurcation and chaos for a certain range of the system parameters. The complexity and predictability of the system are characterized by Lyapunov exponents and Kaplan?CYork dimension. It is shown that, for some suitably chosen system parameters, the system shows hyperchaos even for a small or moderate delay. Finally, we set up an experiment to implement the proposed system in electronic circuit using off-the-shelf circuit elements, and it is shown that the behavior of the time delay chaotic electronic circuit agrees well with our analytical and numerical results.     

Single amplifier biquad based autonomous electronic oscillators for chaos generation

Two simple autonomous chaotic electronic circuits have been proposed in this paper. The core of each of the circuits consists of a single amplifier biquad (SAB). We have proposed two configurations of converting this SAB into chaotic oscillators using suitable passive nonlinear element and a storage element in the form of an inductor. The mathematical models of the proposed chaotic circuits have been constructed, which are fourth order autonomous nonlinear differential equations. The behavior of the proposed circuits has been investigated through numerical simulations, Spice-based circuit simulations and electronic hardware experiments and they agree well with each other. It has been found that both the circuits show complex behaviors like bifurcations and chaos for a certain range of circuit parameters.     

Thermodynamics of a Charged Particle in a Noncommutative Plane in a Background Magnetic Field

Landau system in noncommutative space has been considered. To take into account the issue of gauge invariance in noncommutative space, we incorporate the Seiberg-Witten map in our analysis. Generalised Bopp-shift transformation is then used to map the noncommutative system to its commutative equivalent system. In particular we have computed the partition function of the system and from this we obtained the susceptibility of the Landau system and found that the result gets modified by the spatial noncommutative parameter θ. We also investigate the de Hass–van Alphen effect in noncommutative space and observe that the oscillation of the magnetization and the susceptibility gets noncommutative corrections. Interestingly, the susceptibility in the noncommutative scenario is non-zero in the range of the magnetic field greater than the threshold value which is in contrast to its commutative counterpart. The results obtained are valid upto all orders in the noncommutative parameter θ.     

Structural, dielectric and electromechanical study of Hf-substituted BaTiO3 thin films fabricated by CSD

Hafnium-substituted barium titanate thin films were deposited on platinized silicon substrates. Two different concentrations of solutions (0.1 M and 0.3 M) were used to deposit films of various compositions Ba(Ti_1-x,Hf_x)O₃ (x=0.03, 0.05, 0.07, 0.1, 0.2, 0.3 and 0.4). The microstructure of the films depended on the concentration of the solution. Lower concentration (0.1 M) solutions led to columnar films, but with higher hafnium percent compositions the columnar structure was lost. The films which were derived from the 0.1 M concentration solutions had better dielectric and electrical properties compared to the films derived from a higher concentration (0.3 M). All the films were found to be polycrystalline in nature. The dielectric constant of the films was found to decrease with higher amounts of hafnium substitution. From the I–V characteristics it is noticed that the leakage decreases by almost four orders of magnitude with a hafnium substitution of 40%. The d₃₃ values of the films were between 23 and 5.6 pm/V for the different films. PACS 68.55.-a; 81.20.Fw; 77.84.Dy; 77.55.+f     

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